尼日尔Agadem油田E1油组低阻油层成因分析

尼日尔Agadem油田E1油组普遍发育一套典型的低阻可疑层,在开发过程中,由于对其成因、含油性及产能认识不清,一直未引起足够重视。为了寻求一期油田的稳产接替潜力,针对该套低阻可疑层,采用宏观因素控微观分析的宏观、微观相结合的低阻油层分析方法,通过圈闭幅度和沉积环境等宏观地质成因分析,明确了目的层所处的三角洲前缘末端弱水动力沉积环境为低阻层的主控成因;综合利用岩心、测井及分析化验资料,对储层厚度、岩性、黏土矿物、孔隙结构、束缚水饱和度等岩石物理成因分析,明确了研究区发育3种成因类型的低阻油层,砂泥薄互层和束缚水饱和度偏高为低阻油层主要成因。通过试油和生产,证实了低阻可疑层为产能较好的油层,充分证明了对低阻油层成因分析的合理性,为低阻油层的分类识别和评价提供了依据。

Genetic analysis of low resistivity oil layer in E1 oil group in Agadem Oilfield of Niger

There's a set of typical suspicious oil layers with low resistivity developed in E1 oil group of Agadem Oilfield of Niger.Because the oil-bearing property and productive capacity of the suspicious layer with low resistivity are not clear,it has not attracted enough attention in oilfield exploitation.In order to seek how to continue the stable production of stage I,this paper analyzes the genesis of the suspicious layer with low resistivity based on the method of macroscopic analysis controlling and combining with microscopic analysis.Macroscopic analysis,such as trap amplitude,sedimentary environment,shows that the low-energy hydrodynamic depositional condition at the end of delta front is the main geologic genesis of original low resistivity reservoir.Macroscopic rock petrophysics analysis,such as reservoir thickness,lithology,clay mineral,and irreducible water saturation with the core,well log,all kinds of test datum,and so on,shows that the main genesis of low resistivity reservoir is thin sand-mud interbedding and higher irreducible water saturation in the study area;the two micro-geological geneses lead to three-type low resistivity reservoirs in the study area.It's proved that the low resistivity suspicious layer has a better productive capacity by formation test and production,and it also confirms that the research of genesis analysis of the low resistivity layer is reasonable,which provides evidence for the low resistivity reservoir classification identification and reservoir evaluation in the study area.